Fluid amplifiers, such as pneumatic amplifiers, are well-known devices which have a wide range of industrial and commercial applications. For example, fluid amplifiers may be used in sensors, such as product sensors, which detect the presence of a product at a particular station, or in servo systems which move or position an element, such as a switch, in response to a predetermined condition, such as temperature. Pneumatic control devices of general interest are disclosed in Bitzer et al U.S. Pat. No. 3,770,012, Cowan et al U.S. Pat. No. 3,789,864 and Blok et al U.S. Pat. No. 3,598,020.